Read speeds from a USB stick are incomparably slower than most hard drives. The USB 3.0 specification has a theoretical maximum transfer rate of 5Gb/sec (~600MB/s). By comparison, my PCIe 4.0 NVMe (I believe most laptops these days come with NVMe storage? Could be wrong) has a read performance, reported by CrystalDiskMark, of 7.3GB/s (that’s a big B, not a little b, and looking at 1MiB sequential 1 thread 8 queues). In other words, my hard drive’s measured performance is 12x faster than the theoretical maximum throughput of a USB drive. This also doesn’t take into account things like DirectStorage, which some games have started to adopt.
I think realistically games should consider separating the higher quality assets from the low quality assets intended for lower performance systems, and make them separate downloads. HD assets could be a free “DLC” on Steam, for example.